Предмет: Алгебра, автор: antonfomi

Поезд должен пройти 400 км. Когда осталось пройти три четверти этого пути, его задержали на 2,5 часа. Чтобы прийти вовремя, он увеличил скорость на 20 км/ч. Сколько времени, считая задержку, поезд был в пути?

Ответы

Автор ответа: vitokle

300/х = 300/(х + 20) + 2,5

х = 40

100/40 + 2,5 + 300/60 = 10 (часов)

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